While it was very easy to mount a bin/cue file (from the PC world) in Toast Titanium 5, the "Mount" button when you drag a .bin file on Toast 6 Titanium has vanished. Here is how you mount it with the help of a terminal:
Toast\ 6\ Titanium.app/Contents/MacOS/ToastImageMounter path_to/pc_file.bin
And your disc mounts on your desktop. If you want to know the options of the Toast Image Mounter, launch it in the terminal without argument.